The Synthesis, Characterization And Properties Of Hierarchical Mesoporous Zirconium Phosphonate

A kind of organic-inorganic hybird materials of hierarchicalmesoporous ternary zirconium phosphonate named as NTAZP wassynthesized by using nitrilotris（methylene）-triphosphonic acid （ATMP）and zirconium dichloride oxide octahydrate without any surfactant, whoseformula was Zr₃(C₃H₉O₁₂NP₃)₂·2H₂O. This materials revealed manyregular little spheres with lobular lamellas by enlarging the surface ofglobule, and the average diameter of every sphere is about6.0μm. Thepores that centered at about2.70nm all existed in these leaves. Theaccumulation of these2.70nm mesoporous form a multimodalmesoporous structure with pore diameter between20and30nm. Thishybrid materials combinated with the properties of organic and inorganiccomponents, and displayed full functions by making a large quantity offine pores inside the materials.The application of mesoporous NTAZP was the adsorption toPb²⁺,Cu²⁺,Cd²⁺,Ca_<sup>2+and Mg2+in water. The sorption behaviors of theabove five ions were studied including adsorption kinetics and thermodynamics, and various factors that affect the sorption behaviorssuch as adsorbate at various initial concentrations, reaction at differenttemperature and pH. Combined with the results by XRD, SEM, XPS,FT-IR, the adsorption mechanism was explored. The results showed thatNTAZP was a good adsorbent for the adsorption of heavy metal ions.Good adsorption effect to Pb²⁺, Cu²⁺, Cd²⁺was due to the coordinativeinteractions between the metal ions and N atoms inside mesoporouschannel, besides the structure and morphology did not change in contrastto light metal ions. The adsorption of Ca_<sup>2+and Mg2+may be caused byion exchange, which replaced other ions on the charged point originallyanchored on NTAZP, resulting in the damage of structure and morphology.Adsorption kinetics date show that the adsorption to Pb²⁺,Cu²⁺,Cd²⁺,Ca_<sup>2+and Mg2+in water can be described by pseudo-first order kinetic modeland double exponential function model, and correlation coefficientreached above0.95. The adsorption date of Pb²⁺,Cu²⁺,Cd²⁺can be fittedby Langmuir isotherm, and the date of Ca_<sup>2+and Mg2+can be fitted byFreundlich isotherm successfully.The other application of mesoporous NTAZP was the preparation of asupported Fe³⁺catalyst with different iron content. The researchsuggested that the loading process of Fe³⁺existed an optimal adsorptiontime and temperature. The Fe³⁺-based catalyst were characterized by BET,SEM, FT-IR, XPS. It was found that ferric species were mainly anchored on NTAZP via their coordinative interactions between Fe³⁺and N atomsinside mesoporous channel, and the structure and morphology of NTAZPdid not change after loading. These supported ferric species NTAZP werefound catalytic activity for formaldehyde oxidation. A series of catalyticactivity tests determined the best catalytic conditions. The appropriatecontent of loading iron was0.30mmol/g and catalytic temperature was50℃. The entire catalytic process can achieve the high-efficiencyconversion of formaldehyde oxidation above50℃. The catalyticmechanism was referred to as a classic Fenton-like treatment. Themixture systems of NTAZP-Fe³⁺and H₂O2can oxidize HCHO by OH produced from H₂O2. The Fe³⁺-based catalyst can also avoid Fe³⁺into thewater to prevent secondary pollution.Alternatively hierarchical meso-/macroporous structure of hybridzirconium phosphonate materials was synthesized by usingbis（hexamethylenetriamine）-penta （methylenephosphonic acid） andzirconium dichloride oxide octahydrate without any surfactant as well asNTAZP. The formula of the hybrid material （named as BHAZP） wasZr5(C₁₇H₄₄O₁₅N₃P₅)_0.6·2H₂O. The sample possess a uniform macroporous（500-2000nm） structure of mesoporous （2-3nm） framework, which wascharacterized by SEM, TEM, N2sorption, XRD, TGA-DSC, elementalanalysis, XPS, and FT-IR spectroscopy techniques.